Bullwhip Effect – Logistic Stability Examination in Serial and Arborescent Topologies with Demand Uncertainty and Delay

2021 ◽  
Vol 1 (1) ◽  
pp. 68-80
Author(s):  
Adam Dziomdziora ◽  
Przemysław Ignaciuk
Keyword(s):  
Distribution System ◽  
Demand Uncertainty ◽  
Bullwhip Effect ◽  
Operating Conditions ◽  
Practical Significance ◽  
Transport Delay ◽  
Numerical Tests ◽  
The Face ◽  
Stability Examination ◽  
Basic Configuration

The paper analyzes the formation of the bullwhip effect in logistic systems as a significant threat to preserving stability in the face of non-negligible goods transport delay and uncertainty of demand and stock records. The popular order-up-to policy is selected as the method governing the goods flow. A dynamic model of entity interaction is constructed and examined, first, analytically, then in numerical tests for various scenarios of practical significance, e.g., a supply chain with external and local demand signals or real-world European goods distribution system. It has been found that the order-up-to policy does not trigger the bullwhip effect despite the delays in the goods delivery in the nominal operating conditions in supply chains. However, in networked environments, even the basic configuration triggers the bullwhip effect.

Analysing integration issues of the microgrid system with utility grid network

2021 ◽  
Vol 22 (1) ◽  
pp. 113-127
Author(s):  
Mulualem Tesfaye ◽  
Baseem Khan ◽  
Om Prakash Mahela ◽  
Hassan Haes Alhelou ◽  
Neeraj Gupta ◽  
...  
Keyword(s):  
Renewable Energy ◽  
Distribution System ◽  
Reactive Power ◽  
Renewable Energy Sources ◽  
Operating Conditions ◽  
Control Mode ◽  
Voltage Source ◽  
Modulation Scheme ◽  
Main Challenge ◽  
Utility Grid

Abstract Generation of renewable energy sources and their interfacing to the main system has turn out to be most fascinating challenge. Renewable energy generation requires stable and reliable incorporation of energy to the low or medium voltage networks. This paper presents the microgrid modeling as an alternative and feasible power supply for Institute of Technology, Hawassa University, Ethiopia. This microgrid consists of a 60 kW photo voltaic (PV) and a 20 kW wind turbine (WT) system; that is linked to the electrical distribution system of the campus by a 3-phase pulse width modulation scheme based voltage source inverters (VSI) and supplying power to the university buildings. The main challenge in this work is related to the interconnection of microgrid with utility grid, using 3-phase VSI controller. The PV and WT of the microgrid are controlled in active and reactive power (PQ) control mode during grid connected operation and in voltage/frequency (V/F) control mode, when the microgrid is switched to the stand-alone operation. To demonstrate the feasibility of proposed microgrid model, MATLAB/Simulink software has been employed. The performance of fully functioning microgrid is analyzed and simulated for a number of operating conditions. Simulation results supported the usefulness of developed microgrid in both mode of operation.

scholarly journals Modeling the City Distribution System Reliability with Bayesian Networks to Identify Influence Factors

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Hao Zhang ◽  
Liyu Zhu ◽  
Shensi Xu
Keyword(s):  
Bayesian Networks ◽  
Bayesian Network ◽  
System Reliability ◽  
Distribution System ◽  
Complex Problem ◽  
Practical Significance ◽  
Correlation Degree ◽  
Urban Distribution ◽  
Distribution System Reliability ◽  
The City

Under the increasingly uncertain economic environment, the research on the reliability of urban distribution system has great practical significance for the integration of logistics and supply chain resources. This paper summarizes the factors that affect the city logistics distribution system. Starting from the research of factors that influence the reliability of city distribution system, further construction of city distribution system reliability influence model is built based on Bayesian networks. The complex problem is simplified by using the sub-Bayesian network, and an example is analyzed. In the calculation process, we combined the traditional Bayesian algorithm and the Expectation Maximization (EM) algorithm, which made the Bayesian model able to lay a more accurate foundation. The results show that the Bayesian network can accurately reflect the dynamic relationship among the factors affecting the reliability of urban distribution system. Moreover, by changing the prior probability of the node of the cause, the correlation degree between the variables that affect the successful distribution can be calculated. The results have significant practical significance on improving the quality of distribution, the level of distribution, and the efficiency of enterprises.

ANALYSIS OF THE INFLUENCE OF ELEMENTS OF THE DIESEL COOLING SYSTEM ON ITS THERMAL STABILIZATION BY MEANS OF COMPUTER MODELING

2021 ◽  
Vol 75 (4) ◽  
pp. 3-12
Author(s):  
Zayats Yuriy Aleksandrovich ◽  
◽  
Zayats Tatiana Mikhailovna ◽  
Savelyev Maksim Anatolevich ◽  
◽  
...  
Keyword(s):  
Life Cycle ◽  
Computer Modeling ◽  
Cognitive Modeling ◽  
Cooling System ◽  
Target Function ◽  
Thermal Stabilization ◽  
Cognitive Models ◽  
Operating Conditions ◽  
Practical Significance ◽  
Mechatronic Systems

Logistics support of products at all stages of the life cycle is gaining increasing influence. This is facilitated by the increasing complexity of structures, a large number of elements, the intro-duction of mechatronic systems. Under these conditions, the relevance of developing methods for analyzing the design of samples increases. The developed model for analyzing the diesel cooling system is based on the principles of cognitive modeling. The practical significance of cognitive models is shown, which consists in the possibility of predicting changes in the influence of system elements on the target function in various operating conditions.

scholarly journals Real-Time Human in the Loop MBS Simulation in the Fraunhofer Robot-Based Driving Simulator

2014 ◽  
Vol 61 (2) ◽  
pp. 270-285 ◽  
Author(s):  
Michael Kleer ◽  
Andrey Gizatullin ◽  
Klaus Dreßler ◽  
Steffen Müller
Keyword(s):  
Real Time ◽  
Driving Simulator ◽  
Practical Significance ◽  
Time Model ◽  
Test Drive ◽  
The Real ◽  
Transport Delay ◽  
Human In The Loop ◽  
Acceleration Signal ◽  
Time Calculation

Abstract The paper encompasses the overview of hardware architecture and the systems characteristics of the Fraunhofer driving simulator. First, the requirements of the real-time model and the real-time calculation hardware are defined and discussed in detail. Aspects like transport delay and the parallel computation of complex real-time models are presented. In addition, the interfacing of the models with the simulator system is shown. Two simulator driving tests, including a fully interactive rough terrain driving with a wheeled excavator and a test drive with a passenger car, are set to demonstrate system characteristics. Furthermore, the simulator characteristics of practical significance, such as simulator response time delay, simulator acceleration signal bandwidth obtained from artificial excitation and from the simulator driving test, will be presented and discussed.

scholarly journals Analisis Bullwhip Effect pada Rantai Supply dengan Model Q Menggunakan Pendekatan Hadley-Within di PT. XYZ Medan

2019 ◽  
Vol 2 (4) ◽  
Author(s):  
Martha Purnama Sari Panggabean ◽  
Dimas Akmarul Putera ◽  
Nursafwah
Keyword(s):  
Supply Chain ◽  
Inventory Control ◽  
Distribution System ◽  
Control Policy ◽  
Bullwhip Effect ◽  
Product Distribution ◽  
Soft Drinks ◽  
Inventory Cost ◽  
Inventory Control Policy ◽  
Q Model

PT. XYZ adalah perusahaan yang bergerak didalam pembuatan kemasan botol minum. Pendistribusian produk dilakukan PT XYZ menggunakan data historis berdasarkan jumlah permintaan pada tahun 2013 dan 2014. Data tersebut menunjukkan bahwa terjadinya perbedaan hasil. Tahun 2013 memiliki jumlah permintaan yang lebih rendah dari tahun 2014. Informasi terdapat bahwa perlu dilakukan pengevaluasian karena didalam rantai produksi terdapat bullwhip effect. Terdapat nilai bullwhip Effect menujukan bahwa nilai bullwhip effect untuk distributor Indomaret, Carrefour, dan rantai manufakturnya masing-masing sebesar 0,5303; 0,2967, dan 0,5114. Usulan perbaikan dapat diatasi yaitu dengan model Q yang berfungsi menggendalikan persediaan pada rantai pasok dengan metodeHadley-Within. Perhitungan pengendalian persediaan untuk distributor Indomaret, Carrefour, dan rantai manufakturnya masing-masing sebesar 1,0721; 1,100; dan 1,0714. Hasil dari perhitungan menujukan bahwa terjadi keseimbangan antara penjual dan pembeli sehingga biaya pun dapat dihematkan pada PT XYZ.   PT. XYZ Medan is manufacturing company that produce soft drinks of beverages in containers. In the product distribution system at PT. XYZ Medan, found that the number of orders based on the result of forecasting in 2013 lower than actual orders at distrbutor and manufacturer in 2014. Distorsion of information on this order can evaluate the indication of bullwhip effect in supply chain. Based on the result calculation of bullwhip effect, found that the value of bullwhip effect for Indomaret distributor, Carrefour, and supply chain of manufacturer each of 0,5303; 0,2967, and 0,5114. Proposed improvements to predominate bullwhip effect that is by doing inventory control policy with Q model using Hadley-Within approach. The value of bullwhip effect aftre doing inventory control policy for Indomaret distributor, Carrefour, and supply chain of manufacturer each of 1,0721; 1,100; dan 1,0714. The value of bullwhip effect which is close to one shows that the variance between the number of the order and the number of the demand nearly balanced so as to save the inventory cost at PT. XYZ Medan.

scholarly journals Time-series genome-centric analysis unveils bacterial response to operational disturbance in activated sludge

2019 ◽  
Author(s):  
María Victoria Pérez ◽  
Leandro D. Guerrero ◽  
Esteban Orellana ◽  
Eva L. Figuerola ◽  
Leonardo Erijman
Keyword(s):  
Growth Rate ◽  
Time Series ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Microbial Communities ◽  
Wastewater Treatment Plant ◽  
Treatment Plant ◽  
Operating Conditions ◽  
The Face

ABSTRACTUnderstanding ecosystem response to disturbances and identifying the most critical traits for the maintenance of ecosystem functioning are important goals for microbial community ecology. In this study, we used 16S rRNA amplicon sequencing and metagenomics to investigate the assembly of bacterial populations in a full-scale municipal activated sludge wastewater treatment plant over a period of three years, including a period of nine month of disturbance, characterized by short-term plant shutdowns. Following the reconstruction of 173 metagenome-assembled genomes, we assessed the functional potential, the number of rRNA gene operons and thein situgrowth rate of microorganisms present throughout the time series. Operational disturbances caused a significant decrease in bacteria with a single copy of the ribosomal RNA (rrn) operon. Despite only moderate differences in resource availability, replication rates were distributed uniformly throughout time, with no differences between disturbed and stable periods. We suggest that the length of the growth lag phase, rather than the growth rate, as the primary driver of selection under disturbed conditions. Thus, the system could maintain its function in the face of disturbance by recruiting bacteria with the capacity to rapidly resume growth under unsteady operating conditions.IMPORTANCEIn this work we investigated the response of microbial communities to disturbances in a full-scale activated sludge wastewater treatment plant over a time-scale that included periods of stability and disturbance. We performed a genome-wide analysis, which allowed us the direct estimation of specific cellular traits, including the rRNA operon copy number and the in situ growth rate of bacteria. This work builds upon recent efforts to incorporate growth efficiency for the understanding of the physiological and ecological processes shaping microbial communities in nature. We found evidence that would suggest that activated sludge could maintain its function in the face of disturbance by recruiting bacteria with the capacity to rapidly resume growth under unsteady operating conditions. This paper provides relevant insights into wastewater treatment process, and may also reveal a key role for growth traits in the adaptive response of bacteria to unsteady environmental conditions.

scholarly journals A Novel Hybrid Technique of Frequency Control for Distributed Energy Resources

2021 ◽  
Vol 40 (1) ◽  
pp. 180-204
Author(s):  
Hasham Khan
Keyword(s):  
Power Distribution ◽  
Distribution System ◽  
Energy Demand ◽  
Frequency Control ◽  
Industrial Sector ◽  
Operating Conditions ◽  
Small Scale ◽  
Hybrid Technique ◽  
Operating Characteristics ◽  
Power Distribution System

The rapid increase in the population and fastest development in the industrial sector has increased the energy demand throughout the world. Frequent outages and load shedding has seriously deteriorated the efficiency of the electrical power distribution system. Under such circumstances, the implementation of Distributed Generation (DG) is increasing. Small hydel generators are considered as the most-clean and economical for generating electrical energy. These are very complex nonlinear generators which usually exhibits low frequency electromechanical oscillations due to insufficient damping caused by severe operating conditions. These DGs are not connected to the utility in many cases because, under varying load, they cannot maintain the frequency to the permissible value. This work presents detailed analysis of operating characteristics and proposes a hybrid frequency control strategy of the small hydel systems. The simulation and testing is performed in MATLAB, the results verified the improved performance with the recommended method. The proposed method conserves half of the power consumption. The control scheme regulates the dump load by connecting and disconnecting it affectively. The application of presented methodology is convenient in the deregulated environment, especially under the severe shortage of energy. The proposed model keeps the frequency of system at desired level. It reduces the noise, thereby improving the response time of the designed controller as compared to conventional controllers. The innovative scheme also provides power for small scale industrial, agricultural and other domestic application of far-off areas where the supply of utility main grid is difficult to provide. The recommended scheme is environmental friendly and easy to implement wherever small hydel resources are available.

Overview of methods for controlling the parameters of the tracking mode of a multifunctional radar station

2021 ◽  
Vol 8 ◽  
pp. 122-135
Author(s):  
P.V. Pustozerov ◽  
A.L. Priorov
Keyword(s):  
Quality Criteria ◽  
Subject Area ◽  
Operating Conditions ◽  
Practical Significance ◽  
Radar Station ◽  
Tracking Mode ◽  
Probing Signal ◽  
Scope Of Application ◽  
Mathematical Equations ◽  
Control Criteria

Problem statement. With the development of devices for electronic control of the spatial position of the antenna radiation pattern, it became possible to control the time and duration of probing the radar station of various angular directions. There are many works based on the use of this principle to solve various radar tasks, in particular, to implement the target tracking mode. However, there is no general overview of the developed methods for controlling the parameters of the maintenance mode, the conditions and restrictions introduced in them, control and optimization criteria, as well as the scope of application. Goal. Analysis of the main methods of controlling the parameters of the tracking mode of a multifunctional radar station, including the control criteria used. Results. The analysis of the main methods of controlling the time of probing a target by a radar station, the duration of its probing pulses and signal is carried out. All methods are combined into several groups, the conditions and restrictions introduced during their development are defined. The quality criteria on the basis of which they are synthesized are analyzed. Practical approaches to calculating the parameters of the tracking mode of modern multifunctional radar stations are considered. The directions of further research of the subject area under consideration are formulated. Practical significance. The scientific and methodological apparatus used in calculating the parameters of the tracking mode of multifunctional radar stations is determined. Mathematical equations are given for calculating the duration of the probing signal and the time of probing the target. A set of parameters that must be taken into account when synthesizing control methods is determined. The applicability of the methods in various operating conditions of the radar station is evaluated.

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